Liquid level switch



Patented Sept. 1.3, 1949 f 2,481,612 LIQUID LEVEL SWITCH Ralph A,Nicholson, Chicago, Ill., assignor to Raymond T. Moloney, Chicago, Ill.

Application August 20, 1945,' Serial No. 611,634

2 Claims.

This invention pertains broadly to liquid level kcontrol devices, andhas as its principal object the provision of a highly elicient andsimpliiied control of this character especially suited for use vwithbeverage dispensing equipment utilizing carbonated water, it beingunderstood, however, that the control is not limited to such applicationor use.

Equipment designed for dispensing carbonated water or beveragesvcommonlyincludes a receiver for the water or liquid and a connection to thisreceiver from a source of carbonatlng gas, such arrangements frequentlybeing designated in the art as carbonators or mixers, this practicearising from the commercial expediency of distributing the carbondioxide gas in replaceable drums or cylinders Vwhich are replaced whenexhausted by fully charged cylinders. n

Heretofore, elaborate level rcontrol arrangements of pressure-sensitivevalves, switches, flotation devices and the like have been employed forvcontrolling the operation of a pump to force water into the carbonatoragainst the pressure of the carbonating gas, and such priorarrangements, in

addition to being relatively complex and costly, as

well as bulky or space-consuming, require careful adjustment,supervision. and frequent servicing,

The present invention provides a control which is very small, compact,simple, and inexpensive; it

is also highly reliable in operation, sensitive to 'exposed to the gaspressure and the liquid head pressure, in opposition, and jointlydisplaced to actuate a switch when the head-pressure falls below adesired value;

Another object is the provision of a pressure- Vsensitive switch ofgeneral application, and

especially suited to installation on a carbonator or the like, andincluding a chamber having a pair 'of jointly movable diaphragrnstherein and sealed so that the chamber is divided into a centralcompartment in which the switch means 'is situated for actuationresponsive to displacement of the diaphragme in onedirection, togetherwith separatelysealed compartments into one of which leads acommunication with the gas pressure in the carbonator, and into theother of which the head of water in the carbonator communicates with oneof the diaphragms, such that Iwhen the head of water yfalls below thedesired point, the diaphragms are displaced by gas pressure and/orspring means to actuate the switch and start the liquid pump motor toretore the level.

@ther objects andV aspects of novelty in the nvention relate to detailsof construction and operation of the preferred embodiment describedhereinafter in view of the annexed drawing in which: l

ig. 1 is a vertical section through a carbonating receiver and the novelcontrol means;

Fig. 2 is a horizontal section through the control means along lines2--2 of Fig. 1.

Referring to Fig. l, a sealed carbonating receiver it is provided withconnection Il leading to the liquid or water supply (not shown), fromwhich the liquid is pumped by an electrically driven or controlled pump,not shown, of which there are numerous types known in the art.

.il conduit or connection l2 leads from the receiver, at the topthereof, to the usual supply cylinder of carbonating gas underconsiderable pressure, 30 pounds or more, the purpose of theelectrically driven or controlled pump means being force the water fromthe supply source into the receiver against this gas pressure, the gasand water or other liquid or beverage becoming intermingled in thereceiver, and the gas tending to force the water from the receiver intothe outlet cr dispensing line connection I4 near the bottom or" thereceiver.

In the illustrative embodiment, it is assumed that the liquid level isto be maintained at the point l5 in the receiver, and the novel meansfor accomplishing this includes the control generally indicated at l 6.

In a preferred formr of construction, the control !6 includes a centralmetal ring il having upper and lower flanges I8' and I9, and recessed orconcaved end vcaps or pieces 20 and ill each having ilange portions 28Aand ZIA adapted to seat against the flange portions of the central ring,thus forming a main chamber which is attached to the bottom of thecarbonator or receiver lil by welding or the like of upper end piece 2lto the bottom of the receiver, there being an opening 21B ofpredetermined size in this upper end piece, which opening registers witha like opening lA in the bottom of the receiver.

Interiorly of the main control chamber is an upper membrane or diaphragmclamped in sealed condition between flanges I8 and 2IA by screw means 25in the latter, while a similar diaphragm 27 is sealingly clamped in thelower part of the main chamber between anges I9 and 20A, as by screws28.

The membranes or diaphragms 25 and 21 thus divide the main chamber intoa central compartment or chamber 30, which is sealed cfr from an uppercompartment or chamber 3l by upper diaphragm 25, and a lower compartmentor chamber 32, which is sealed off by lower diaphragm 21.

The two diaphragms are interconnected by a stud in axial alignment withthe centers of these diaphragms and attached to the latter by screws Sethrough sealing washers 40, so that the diaphragms can move jointly up,and down.

Control switch means for rthe liquid pump is situated in the centralchamber, and includes. a pair of switch blades 42 and 43 secured andbiased in normally open-circuitv condition between the usual insulatingwafers 44 on a mounting bracket 45 welded to the interior of thiscentral chamber, there being also an operating blade 46 having aninsulating stud 4i adapted to bear up against the lower switch blade 43to push the latter into cir cuit-closing engagement with the companionswitch blade e2, there being an arm or extension 48 on the operating armextending into driving engagement with the diaphragm-connecting stud 35,as by engagement in a slot 49 therein. Thus, when stud 35 movesupwardly, as by displacement upwardly of the diaphragms, switch blades42-43 will be closed together by upward movement of insulated stud 'l.

Means for causing operation of the switch 42- d3 responsive to loweringof the liquid level inthe receiver, includes a small spring expandingupwardly against the lower diaphragm assembly in the lower chamber 32and of suiiicient strength to displace this lower diaphragm upwardly toclose switch 1li-[i3 provided the head of water above openings IBA--IBbearing on the upper diaphragm 25 is less than aV predetermined amount.

Normally, when the liquid level is at the point I5, thisdiaphragm-operating head is adequate to resist the upward eiiort ofspring 50, but when the water level falls to the point IEA, the head ofwater (indicated in dash-dot lines in the receiver) is insucient tooverbalance spring 50, and the latter pushes the lower diaphragm, andhence the upper one as well, upwardly causing switch operating arm d8 tobe carried upwardly with a consequent closing of switch 42--133 by studlil, thus closing a pump motor operating circuit via conductors eZA and43A.

In order to assure positive operation of the control i6 at all times andunder all practical gas operating pressures in the dispensing system,the gas pressure in receiver I is balanced-out by means of a balancingconnection or line 6U communicating from the lower chamber 32, as atlil, into the upper portion of the receiver, and above the normal waterlevel l5 therein, as at 62.

Since the gas pressure in receiver i6 is exerted downwardly against theupper diaphragm 25, and simultaneously upwardly against the lowerdiaphragm 21, in opposition to the effort against the upper diaphragm,the net effect of this gas pressure on the diaphragms is substantiallyzero, and the diaphragm system is therefore sensitive only to variationsin the head of liquid in receiver I0, and a highly satisfactorysensitivity to variations in liquid level becomes possible by selectionof an 4 appropriate spring tension for spring 50 depending on the levelwhich is to be maintained.

The central chamber 30 is sealed off and no sealing precautions arenecessary for switch leads dBA-43A; and there is adequate room in thischamber for installation of various types of switch other than thatshown, it being possible to employ a small snap-action switch, ifdesired, in place of the blade switch described.

As heretofore mentioned, switch leads 42A- 43A are adapted to beconnected in the control circuit (not shown) for an unshown pump motorto force replenishing supply of water into the carbonator or receiverI0. Such motor pump arrangements are known in the art and do not per seconstitute part of the invention, the principal invention being in theprovision of a switch means actuated by a liquid head subjected to gaspressure, and means for balancing out the effects of the gas pressure sothat the liquid level or head is the controlling factor, the` inventionalso extending todetails of the control device per se.

The foregoing specic description is not in.- tended to be limitingexcepting as may be ex.- pressly provided by the appended claims fairlyconstrued in the light of the prior art.

Having thus described my invention, what I claim as new and desire toAprotect by Letters Patent of the United States is:

1. A device of the class described comprising upper and lower chambers,said upper chamber adapted to contain liquid and gas under pressure,said lower chamber being ot unitary con;- struction and having a pair'ofparallel, spacedapart diaphragms one above the other therein anddividing said lower chamber into an upper compartment, a lowercompartment, and a middie compartment, said compartments all sealed 01Tfrom eachother and saidupper compartment communicating. vertically intosaid upper chamber such that a head of liquid and gas therein exerts aforce on the uppermost of said dia'- phragms, a pressure-equalizing gasconnection between the upper region of said upper chamber and the saidlower compartment, and a switch situated in said middle compartment,wherein itis sealed against moisture and gas fromv said othercompartments, and means mainly in said middle compartment opera-tivelyinterconnecting said diaphragms with each other and with said switch foroperation of the latter responsive to displacements of said diaphragms,jointly, predetermined amounts,.together with spring means yieldinglyurging saidl diaphragms upward with force to be ba-lancedj by adetermined volume of liquid in. said upper chamber.

2. A liquid level control comprising upper, lower, and median chamberVportions formed to iit together and define a unitarychamber..a diaphragmsealingly clamped between said, upper and median chamber portionsandanother diaphragm clamped sealingly between saidv lower and media-nchamber portions, said. diaphragms being in approximate parallelism and.one in alignment above the other such ,thatgsaidfunitary chamber isdivided into upper, middle, andlower compartmentssealed of from eachotherstud means operativelyv interconnecting said diaphragms in saidmiddle compartment, a switch in said middle compartnnant`:mdfoperatviely1 as.- scciated with said diaphragms by means or aprojection therefrom extending into a slot in said stud suchthat4baclrand.v forth motions of the stud responsive to correspondingAdisplacements of said diaphragms will actuate said switch, REFERENCESCITED spring means normally urging said diaphragms jointly in adirection toward said upper -com- The following references are of recordin the partment, a pressure opening communicating into 111e 0f thispatenti said upper compartment for communicating` a 5 UNITED STATESPATENTS head of liquid pressure to the upper--most dlaphragm, andpressure-balancing means includ- Number N a'me Date ing an opening intosaid lower compartment for 916,957 Dur (11n, J1 Mal- 30, 1909introduction therein of a pressure acting on said 973,103 Basllan DBC.6, 1910 head of liquid pressure .but in addition to the 1o 1,847,086Gargan Mar. 1, 1932 latter, such that the loading effect of said addi-1,952,265 Leland Mal'- 27, 1934 tional pressure on said diaphragms issubstanti- 2,031,502 Powell Fell 18, 1936 ally balanced out, said switchbeing sealed off 2359,163 SOIIIGS et al Sept. 26, 1944 from substancesin either of the upper or lower compartments. 15

RALPH A. NICHOLSON.

